243505553 has 2 divisors, whose sum is σ = 243505554. Its totient is φ = 243505552.

The previous prime is 243505523. The next prime is 243505573. The reversal of 243505553 is 355505342.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 227768464 + 15737089 = 15092^2 + 3967^2 .

It is a cyclic number.

It is not a de Polignac number, because 243505553 - 2¹² = 243501457 is a prime.

It is not a weakly prime, because it can be changed into another prime (243505523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121752776 + 121752777.

It is an arithmetic number, because the mean of its divisors is an integer number (121752777).

Almost surely, 2^243505553 is an apocalyptic number.

It is an amenable number.

243505553 is a deficient number, since it is larger than the sum of its proper divisors (1).

243505553 is an equidigital number, since it uses as much as digits as its factorization.

243505553 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 45000, while the sum is 32.

The square root of 243505553 is about 15604.6644629098. The cubic root of 243505553 is about 624.4576013154.

The spelling of 243505553 in words is "two hundred forty-three million, five hundred five thousand, five hundred fifty-three".